German Patent No. 718 252 relates to a process for producing electrodeposited coatings of silver-tin alloys with a tin content of 5 to 20%, employing an alkaline cyanide bath containing tin in the form of stannate or tetrachloride and current densities of 0.1 to 1 a/dm.sup.2. The baths may also additionally contain potassium gold cyanide and/or palladium chloride; in this case silver-tin alloys with 2 to 20% gold and/or palladium are deposited.
German Patent No. 849 787 proposes oxyacids, amino acids or salts of these acids as complexing agents suitable for the electrodeposition of alloys of silver with germanium, tin, arsenic or antimony from cyanidic electrolytes. The deposited coatings are hard and are distinguished by high luster, because of which the subsequent polishing is made easier even with thick deposits. It is not possible to cite general threshold values for the addition of germanium, tin, arsenic or antimony, since they are subject to strong fluctuations in connection with the composition of the baths and the working conditions. It is possible to add brighteners to the baths; however, the effects remain weak in general.
German Laid-Open Patent Application No. 1 153 587 discloses a cyanide bath for the electrodeposition of alloys in which the silver is in the form of potassium silver cyanide and which contains the alloy elements--mainly tin, lead, antimony and bismuth--in the form of complexes with an aromatic dihydroxy compound. The bath is operated at a current density of 0.5 to 1.5 A/dm.sup.2 and at room temperature. The current density can be increased to more than 2 A/dm.sup.2 by the addition of brighteners. This published application also discloses that aliphatic oxycarboxylic acids, such as oxalic acid or tartaric acid, and aliphatic, straight-chain polyoxy compounds, such as sorbitol, dulcitol or glycerol have been used as complexing agents for the deposition of alloys from cyanide silver baths.